Martial arts should be a mandatory life skill.
Activities and sports like Hockey, Baseball, Soccer, Gymnastics, Girl/Boy Scouts etc… are all great hobbies and pastime activities and my kids can choose whatever activities or sports they want to participate in.
Swimming lessons are categorically different. Swimming is a mandatory life skill and non-negotiable. Why? Because sooner or later our children will be exposed to water, (be it a pool, lake, river or ocean) and not having basic swimming skills and confidence around the water will hold them back and, even more importantly, could be potentially fatal. They don’t need to be Olympic swimmers, but they need enough basic skills to tread water and survive but ideally are competent enough that they don’t have to be nervous or fearful around water.
You’ll see a parallel if you apply that same lens to self-defense training in the martial arts. Sure, martial arts can be a great sport, with all the benefits of traditional sports, but if done correctly, also teach self-defense which is an essential life skill. In your child’s lifetime, they will almost certainly face the threat of bullying and/or physical violence (sometimes unavoidably, or through no fault of their own).
When you are attacked, just like in the water, it doesn’t matter how hard you try, without proper training and technique you will panic, flail, thrash & most likely drown. We put our kids in swimming lessons to prepare them, so they can be in the water without fear and tread water if they get in over their heads. The day your child gets confronted by a bully or other human predator, ask yourself; have you given them the tools & confidence to stay calm, protect themselves and survive or have they been thrown in the deep end to fend for themselves?